Multiple Host-Guest Interactions in Metal-Organic Frameworks Constructed by Inverted Calix[4]arenes

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Nanotechnology

Background:

• Calixarenes are macrocyclic compounds with inherent host-guest properties.
• The potential of calixarenes as building blocks for supramolecular assemblies, particularly metal-organic frameworks (MOFs), remains underexplored.

Purpose of the Study:

• To utilize a carboxyl-modified azocalix[4]arene (CAC4A) as an organic ligand for constructing novel MOFs.
• To investigate the structural diversity and adsorption properties of calixarene-based MOFs.

Main Methods:

• Synthesis of three calixarene-based MOFs using La³⁺, Ca²⁺, and Mn²⁺ metals.
• Characterization of MOF structures using single crystal X-ray diffraction.
• Evaluation of host-guest interactions and adsorption abilities.

Main Results:

• Three distinct calixarene-based MOFs were successfully synthesized.
• The MOFs exhibit structural diversity due to the low symmetry of calixarene ligands, forming 1D chains or 2D sheets.
• Hierarchical porous structures with enhanced adsorption capabilities were achieved through a bottom-up assembly approach.
• Direct observation of guest molecule (iodine) interactions within the framework pores was possible.

Conclusions:

• Calixarene ligands are effective building blocks for creating structurally diverse and porous MOFs.
• The developed MOFs demonstrate significant potential for host-guest chemistry and adsorption applications.
• This work provides a new strategy for constructing hierarchical porous materials with tunable properties.